AB0307 MERKEL CELL CARCINOMA RECURRENCE RISK IS LOWER IN PATIENTS WITH AUTOIMMUNE DISEASE THAN IN THOSE WITH OTHER TYPES OF IMMUNE SUPPRESSION
Authors: S. Park, D. Hippe, L. Zawacki, M. Bierma, S. Bhatia, L. Zaba, P. Nghiem, N. Singh
Journal: Annals of the Rheumatic Diseases (2022)

Background Merkel cell carcinoma (MCC) is twice as likely to recur in immunosuppressed (IS) patients as in immunocompetent (IC) patients. Iatrogenic IS due to autoimmune disease (AD) may influence prognosis differently than intrinsic IS such as due to hematologic malignancy. Moreover, modification of IS medication may improve prognosis. Objectives Our objective was to evaluate the risk of MCC recurrence among patients with AD diseases relative to other immunosuppressive conditions among 762 MCC patients from an Institutional review board-approved registry. Methods We categorized patients into 3 groups: IS due to AD (IS AD ); IS from other causes (lS non-AD ) such as hematologic malignancy, solid organ transplant, human immunodeficiency virus; or immune competent (n=31, 70, and 661 respectively). IS AD patients were subcategorized into rheumatoid arthritis (RA) (AD RA , n=13) vs. AD except for RA (AD non-RA , n=18). Descriptive statistics were used to compare the features of different characteristics in each group. Kaplan-Meier survival curves were constructed to assess the cumulative incidence of recurrence in different patient groups. In order to estimate the associations between baseline patient characteristics and the risk of MCC recurrence, Fine and Gray regression models were used with death as a competing risk for recurrence. The multivariable models adjusted for age, sex, and extent of MCC at initial presentation. Results Patients with IS AD had lower stage disease (local disease: 58% vs. 36%, p = 0.003) and smaller primary tumors than IS non-AD (&lt;= 2 cm: 83% vs. 57%, p=0.023). After adjusting for age, sex, and stage, IS AD patients (AD RA and AD non-RA ) overall had a 54% higher recurrence rate (hazard ratio (HR): 1.54, p=0.21) than IC patients. In comparison, IS non-AD group had a 165% higher recurrence rate (HR: 2.65, p&lt;0.001) than IC patients (Figure 1). When considered separately, AD RA pts appeared to have a similar recurrence rate as IC pts (HR: 1.19, p=0.76) while AD non-RA pts had a higher recurrence rate (HR: 1.83, p=0.16) relative to IC pts. At the time of MCC diagnosis, 80% (n=24) of AD pts were on IS medication including conventional disease modifying drugs, biologics, or oral steroids. After MCC diagnosis, 22% (5 patients) stopped all immunosuppressive medications. Among patients on biologics, 89% (8/9 pts) elected to stop the drug. Eleven pts with AD experienced recurrences. Our study was underpowered to demonstrate associations regarding use of a particular immunosuppressive medication and MCC recurrence. Figure 1. Cumulative incidence of Merkel cell carcinoma recurrence in different patient groups. AD = autoimmune disease; IS = immunosuppressed; RA = rheumatoid arthritis.There were 4/13, 8/18, 49/70, and 217/661 recurrences in the RA, AD non-RA , other immunosuppressed, and not chronically immunosuppressed groups, respectively. Follow-up time ranged from 26 days to 16 years, with median follow-up times of 4.7 years, 1.6 years, 1.6 years, and 3.9 years for the RA, AD non-RA , other immunosuppressed and not chronically immunosuppressed groups, respectively. Conclusion In this cohort, pts with AD appeared to have a better prognosis than intrinsic IS, with RA conferring very little risk above that for immune competent pts. Acknowledgements I have no acknowledgements to declare. Disclosure of Interests None declared